Thermodynamics of Fe(II)Fe(III) oxide systems I. Hydrothermal Fe3O4

Journal of Chemical Thermodynamics

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Abstract

The heat capacity of a hydrothermally-prepared polycrystalline sample of Fe3O4 was measured from 53 to 350 K, primarily to study the thermophysics of the Verwey transitions. Although the bifurcation of the transition was confirmed, the sample was found to contain traces of manganese. The observed transition temperatures of 117.0 and 123.0 K are 3.7 and 4.2 K higher respectively than those found in pure Fe3O4. Ancillary analytical results are consistent and indicate a stoichiometry of Mn0.008Fe2.992O4 for this material. Characteristics in the transition region are ascribed to dopant effects. ?? 1976.